A wide variety of implantable medical devices (IMDs) that deliver a therapy to or monitor a physiologic or biological condition of a patient, or both, have been clinically implanted or proposed for clinical implantation in patients. An IMD may deliver therapy to and/or monitor a physiological or biological condition with respect to a variety of organs, nerves, muscles or tissues of the patients, such as the heart, brain, stomach, spinal cord, pelvic floor, or the like. The therapy provided by the IMD may include electrical stimulation therapy, drug delivery therapy, or therapy to reduce or eliminate a condition or symptoms of the condition of the patient.
The IMD may wirelessly communicate with another implanted device or an external device. An external device with which an IMD may communicate may be a programming device or a monitoring device (e.g., either attached to the patient or otherwise located near the patient). The information exchanged may be information related to a condition of the patient, such as physiological signals measured by one or more sensors, or information related to a therapy delivered to the patient. This information may be previously stored or real-time information. The IMD may also receive information from the external device, such as configuration information that may be used to configure a therapy to be provided to the patient. An IMD may communicate with another implanted device to control the operation of the other implanted device and/or to receive physiological data sensed by the other implanted device.
In some examples, an IMD wirelessly communicates with an implanted or external device via tissue conductance communication (TCC). During TCC, current is driven through the tissue between two or more electrodes of the transmitting IMD (or external device). The current spreads through the thorax, producing a potential field. The receiving IMD (or external device) may detect the TCC signal by measuring the potential difference between two or more of its electrodes.